2.4km for a 14yo is too much. The school over-estimated young Sinkies capabilities. During army, 2.4km already caused many "well-trained" men to "hey hey chuan". Besides, there could be many causes. The boy either overate, or run with empty stomach, or already sick or had some sort of infection and made worse by dehydration. Every student should be given BP pressure test first before allowing them to start the run. When I was jogging, I also saw many students running along side with me. Some races, some walk, some just stop at interval to rest and the latter is the smart one.